1. Field of the Invention
The present invention generally relates to a micro-electro-mechanical system (MEMS) structure and a method of manufacturing the same.
2. Description of Related Art
Recently, as the integrated circuit (IC) technique has been vigorously developed, an MEMS structure is fabricated through the mature complementary metal oxide semiconductor (CMOS) process technique. In addition, circuit and the MEMS structure are directly integrated on a single chip.
For example, a capacitive microphone structure is formed by a back plate filled with acoustic holes and a sensing film. When a pressure wave of a sound acts on the microphone, the sensing film moves relative to the back plate, such that a capacitance between the back plate and the sensing film is changed. Since the acoustic pressure is actually a slight pressure change, it requires high process accuracy and a high stability of the microphone.
However, recently, the materials formed through the CMOS technique employ a thin film process, such that a single layer of CMOS material used for providing the back plate of the microphone has structural strength issue to be considered.